IDbDataAdapter.SelectCommand IDbDataAdapter.SelectCommand IDbDataAdapter.SelectCommand IDbDataAdapter.SelectCommand Property

Definizione

Ottiene o imposta un'istruzione SQL utilizzata per selezionare i record nell'origine dati.Gets or sets an SQL statement used to select records in the data source.

public:
 property System::Data::IDbCommand ^ SelectCommand { System::Data::IDbCommand ^ get(); void set(System::Data::IDbCommand ^ value); };
public System.Data.IDbCommand SelectCommand { get; set; }
member this.SelectCommand : System.Data.IDbCommand with get, set
Public Property SelectCommand As IDbCommand

Valore della proprietà

Interfaccia IDbCommand utilizzata durante l'operazione di Update(DataSet) per selezionare i record dall'origine dati e posizionarli nel dataset.An IDbCommand that is used during Update(DataSet) to select records from data source for placement in the data set.

Esempi

Nell'esempio seguente viene creata un'istanza della classe OleDbDataAdapter ereditata e vengono impostate SelectCommand le InsertCommand proprietà e.The following example creates an instance of the inherited OleDbDataAdapter class, and sets the SelectCommand and InsertCommand properties. Si presuppone che sia già stato creato OleDbConnection un oggetto.It assumes you have already created an OleDbConnection object.

public static OleDbDataAdapter CreateCustomerAdapter(
    OleDbConnection connection)
{
    OleDbDataAdapter adapter = new OleDbDataAdapter();
    OleDbCommand command;

    // Create the SelectCommand.
    command = new OleDbCommand("SELECT * FROM Customers " +
        "WHERE Country = ? AND City = ?", connection);

    command.Parameters.Add("Country", OleDbType.VarChar, 15);
    command.Parameters.Add("City", OleDbType.VarChar, 15);

    adapter.SelectCommand = command;

    // Create the InsertCommand.
    command = new OleDbCommand(
        "INSERT INTO Customers (CustomerID, CompanyName) " +
        "VALUES (?, ?)", connection);

    command.Parameters.Add(
        "CustomerID", OleDbType.Char, 5, "CustomerID");
    command.Parameters.Add(
        "CompanyName", OleDbType.VarChar, 40, "CompanyName");

    adapter.InsertCommand = command;
    return adapter;
}
Public Shared Function CreateCustomerAdapter( _
    connection As OleDbConnection) As OleDbDataAdapter 

    Dim adapter As OleDbDataAdapter = New OleDbDataAdapter()
    Dim command As OleDbCommand

    ' Create the SelectCommand.
    command = New OleDbCommand("SELECT * FROM Customers " & _
        "WHERE Country = ? AND City = ?", connection)

    command.Parameters.Add("Country", OleDbType.VarChar, 15)
    command.Parameters.Add("City", OleDbType.VarChar, 15)

    adapter.SelectCommand = command

    ' Create the InsertCommand.
    command = New OleDbCommand( _
        "INSERT INTO Customers (CustomerID, CompanyName) " & _
        "VALUES (?, ?)", connection)

    command.Parameters.Add( _
        "CustomerID", OleDbType.Char, 5, "CustomerID")
    command.Parameters.Add( _
        "CompanyName", OleDbType.VarChar, 40, "CompanyName")

    adapter.InsertCommand = command
    Return adapter
End Function

Commenti

Quando SelectCommand viene assegnato a un oggetto creato IDbCommandin precedenza IDbCommand , non viene clonato.When SelectCommand is assigned to a previously created IDbCommand, the IDbCommand is not cloned. Mantiene un riferimento all'oggetto creato IDbCommand in precedenza. SelectCommandThe SelectCommand maintains a reference to the previously created IDbCommand object.

Se non restituisce alcuna riga, nessuna tabella viene aggiunta DataSeta e non viene generata alcuna eccezione. SelectCommandIf the SelectCommand does not return any rows, no tables are added to the DataSet, and no exception is raised.

Si applica a